• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.5
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• pp.1104-1109
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• 2015

Due to the rapid growth in digital contents, it is important for us to design a high speed and secure encryption algorithm which is able to comply with the existing and future needs. This paper proposes an alternative approach for self-decimated LM-128 summation sequence generator, which will generate a higher throughput if compared to the conventional generator. We design and implement a threshold clock-controlled LM-128 and prove that it has a lower clock cycle and hence giving a higher key stream generation speed. The proposed threshold clock-control LM-128 generator consists of 256 bits inner state with 128 bits secret key and initialization vector. The cipher achieves a security level of 128 bits to be adapted to the digital contents security with high definition and high quality.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.10
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• pp.2164-2170
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• 2011

Rapid surge in date quantity lead to increase in storage demand from corporate. The existing SAN with fiber channel is being changed to IP-based SAN environment due to installment and maintenance cost. But the IP-based network still have some similar security problems as existing TCP/IP network. Also, for the security reasons of storage traffic, data are encrypted, but with the existing system, data larger than 10G can't be handled. To address security and speed issue, this paper proposes to a structure applied to IP SAN environment with Parallel Structure Word-based FSR (PS-WFSR) as hardware.

• Journal of information and communication convergence engineering
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• v.8 no.4
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• pp.427-432
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• 2010

The fast-emerging of cloud computing technology today has sufficiently benefited its wide range of users from individuals to large organizations. It carries an attractive characteristic by renting myriad virtual storages, computing resources and platform for users to manipulate their data or utilize the processing resources conveniently over Internet without the need to know the exact underlying infrastructure which is resided remotely at cloud servers. However due to the loss of direct control over the systems/applications, users are concerned about the risks of cloud services if it is truly secured. In the literature, there are cases where attackers masquerade as cloud users, illegally access to their accounts, by stealing the static login password or breaking the poor authentication gate. In this paper, we propose a two-factor authentication framework to enforce cloud services' authentication process, which are Public Key Infrastructure (PKI) authentication and mobile out-of-band (OOB) authentication. We discuss the framework's security analysis in later session and conclude that it is robust to phishing and replay attacks, prohibiting fraud users from accessing to the cloud services.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2240-2250
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• 2016

MIFARE Classic is the most popular contactless smart card, which is primarily used in the management of access control and public transport payment systems. It has several security features such as the proprietary stream cipher Crypto 1, a challenge-response mutual authentication protocol, and a random number generator. Unfortunately, multiple studies have reported structural flaws in its security features. Furthermore, various attack methods that target genuine MIFARE Classic cards or readers have been proposed to crack the card. From a practical perspective, these attacks can be partitioned according to the attacker's ability. However, this measure is insufficient to determine the optimal attack flow due to the refined random number generator. Most card-only attack methods assume a predicted or fixed random number, whereas several commercial cards use unpredictable and unfixable random numbers. In this paper, we propose optimal MIFARE Classic attack procedures with regards to the type of random number generator, as well as an adversary's ability. In addition, we show actual attack results from our portable experimental setup, which is comprised of a commercially developed attack device, a smartphone, and our own application retrieving secret data and sector key.

• Journal of Communications and Networks
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• v.13 no.1
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• pp.1-5
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• 2011

Feedback with carry shift registers (FCSRs) over 2-adic number would be suitable in hardware implementation, but the are not efficient in software implementation since their basic unit (the size of register clls) is 1-bit. In order to improve the efficiency we consider FCSRs over $2^{\ell}$-adic number (i.e., FCSRs with register cells of size ${\ell}$-bit) that produce ${\ell}$ bits at every clocking where ${\ell}$ will be taken as the size of normal words in modern CPUs (e.g., ${\ell}$ = 32). But, it is difficult to deal with the carry that happens when the size of summation results exceeds that of normal words. We may use long variables (declared with 'unsigned _int64' or 'unsigned long long') or conditional operators (such as 'if' statement) to handle the carry, but both the arithmetic operators over long variables and the conditional operators are not efficient comparing with simple arithmetic operators (such as shifts, maskings, xors, modular additions, etc.) over variables of size ${\ell}$-hit. In this paper, we propose some conditions for FCSRs over $2^{\ell}$-adic number which admit fast software implementations using only simple operators. Moreover, we give two implementation examples for the FCSRs. Our simulation result shows that the proposed methods are twice more efficient than usual methods using conditional operators.

• Journal of the Korea Society of Computer and Information
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• v.13 no.5
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• pp.155-162
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• 2008

The security of digital image has become increasingly important with the development of the computing performance and internet. Therefore, the encryption algorithms exploiting chaos signal have recently attracted considerable attentions as a new method of image-encryption techniques. In this Paper, it is demonstrated that two different chaotic systems are synchronized by the methods of noise-induced synchronization. Based on this synchronization method, an image-encryption system is implemented and an image of Seok-Ga-Tap is encrypted as a verification of the performance of our system. The method suggested in this paper in which the noise is used as the key of decryption is superior to the existing methods in the aspect of the degree of encryption. In this paper, we Propose that the method is a new effective encryption algorithm as well as an easily applicable one.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.1
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• pp.71-77
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• 2004

It was proved that Hen is an algebraic ,elation of degree [n(l+1]/2] for an (n, 1)-combine. which consists of n LFSRs and l memory bits. For the summation generator with $2^k$ LFSRs which uses k memory bits, we show that there is a non-trivial relation of degree at most $2^k$ using k+1 consecutive outputs. In general, for the summation generator with n LFSRs, we can construct a non-trivial algebraic relation of degree at most 2$^{{2^{[${log}_2$}n]}}$ using [${log}_2$＋1 consecutive outputs.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.6
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• pp.1237-1246
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• 2021

This paper is about Asynchronous Transfer Mode (ATM) cell security in which an Output Feedback (OFB) mode is applied to an AES block ciphers. ATM cells are divided into user data cells and maintenance cells, and each cell is 53 octets in size and consists of a header of 5 octets and a payload of 48 octets. In order to encrypt/decrypt ATM cells, the boundaries of cells must be detected, which is possible using the Header Error Control (HEC) field in the header. After detecting the boundary of the cell, the type of payload is detected using a payload type (PT) code to encrypt only the user cell. In this paper, a security method for ATM cells that satisfies the requirements of ISO 9160 is presented.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.1
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• pp.99-106
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• 2011

The emerging of ubiquitous computing and healthcare technologies provides us a strong platform to build sustainable healthcare applications especially those that require real-time information related to personal healthcare regardless of place. We realize that system stability, reliability and data protection are also important requirements for u-healthcare services. Therefore, in this paper, we designed a u-healthcare system which can be attached to the patient's body to measure vital signals, enhanced with USN secure sensor module. Our proposed u-healthcare system is using wireless sensor modules embedded with NLM-128 algorithm. In addition, PS-LFSR technique is applied to the NLM-128 algorithm to enable faster and more efficient computation. We included some performance statistical results in term of CPU cycles spent on NLM-128 algorithm with and without the PS-LFSR optimization for performance evaluation.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.11
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• pp.1749-1754
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• 2013

Binary sequences of period $2^n-1$ are widely used in many areas of engineering and sciences. Some well-known applications include coding theory, code-division multiple-access (CDMA) communications, and stream cipher systems. In this paper we analyze different solutions to $x^5+bx^3+b^{2^m}x^2+1=0$ over $GF(2^n)$. The number of different solutions determines frequencies of cross-correlations of nonlinear binary sequences generated by $d=3{\cdot}2^m-2$, n=2m, m=4k($k{\geq}2$). Also we give an algorithm for determination of number of different solutions to the equation.